I have bought a Clip-on BT headset
http://www.expansys.com/product.asp?code=EZ232 because I was worried that having even a low power radio transmitter clipped to the side of my head for any length of time might send me doolally (or even more so!).
I think the clip-on ones (the ones with a short bit of cable with the earpiece on it) are not quite as convenient as the 'Boom' ones. Although does anybody feel a bit if a D*&k walking around with their on-ear BT headset on?
At least with the clip-on I can take the earpiece out but still hear it beep when a call comes through.